Pretty Good Game Engine
Started life as libGDX 3D and Bullet physics demo from "http://bedroomcoders.co.uk/libgdx-bullet-redux-2/", modified to Ashley ECS (entity component system architecture).
Please download assets from: https://www.dropbox.com/sh/1fr6qrnrpe8bjxv/AABPse-gun_l1qdRVZQmPaJ9a?dl=0